1. Field of the Invention
The invention relates to a threaded pipe coupling for connecting a pipe to a connecting part with conical exterior surfaces, particularly for connecting copper pipes in refrigeration technology.
2. Prior Art
The connection nipples used in refrigeration technology typically have a conical exterior surface on their front, connection-side end. Previously the pipe ends were often expanded (raised edges) for sealing pipe joints at such connection nipples. The expanded part of the pipe is then directly clamped between a union nut that can be threaded onto the connection nipple and the connection nipple. Such a clamping then seals the pipe end on the connection nipple. However, one problem in such threaded couplings is that there is an increased risk of crack formation due to the expansion of the pipe and the resulting weakening of the material. With vibrations in particular, cracks and resulting non-sealed areas of the threaded coupling can be created in the expanded region. These problems occur particularly in copper pipes because copper undergoes intensive work-hardening for large deformations. Here, in addition to undesired non-sealed areas, ruptures of the pipe ends can even be produced. The discharged media are environmentally dangerous.                a. As an alternative, special transition pieces with an inner contour adapted to the shape of the connection nipple are soldered to the pipe end. These transition pieces are then likewise clamped between a union nut and the connection nipple. However, this type of connection has the disadvantage that the solder joint is susceptible to vibrations, and the connection can break at the solder joint. Typical solder is also poisonous, and represents a danger to the installer and the environment.        b. To avoid the previously mentioned problems, additional intermediate pieces have also already been used, which are initially threaded to the connection nipple. The corresponding pipe is then mounted on this separate intermediate piece by means of a threaded pipe coupling. However, this type of coupling requires additional components, which is associated with increased costs and assembly expense.        